Portable Millimeter-Wave Communications Device

ABSTRACT

A portable millimeter-wave wireless communications device relies on millimeter-wave spectrum for wireless communications. The millimeter-wave device may be a smart-phone, a laptop computer or a tablet computer. The millimeter-wave device may be a module that is added to an existing portable device such as a smart-phone, a laptop computer or a tablet computer to provide millimeter-wave communications capability. The module may be incorporated into a protective encapsulating case of such portable devices.

RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.15/458,884 filed Mar. 14, 2017, which claims priority to U.S.Provisional Patent Application No. 62/384,064, filed Sep. 6, 2016, andentitled “A PORTABLE MILLIMETER-WAVE WIRELESS COMMUNICATIONS DEVICE”both of which are hereby incorporated by reference in their entirety.

BACKGROUND

The invention relates to wireless communications, and in particular tomillimeter-wave wireless communication devices.

DESCRIPTION OF THE RELATED ART

Current wireless communication systems are based primarily on twostandards: Wide area network (WAN) or cellular standards (e.g., FourthGeneration Long Term Evolution (4G LTE) system); and local area networks(LAN) standards (e.g., IEEE 802.11ac). Wireless LAN systems, hereafterto be referred to as “Wi-Fi”, serve as wireless extensions of wiredbroadband systems and operate in either the license-exempt or the sharedspectrum bands. The 4G LTE cellular systems provide wide areaconnectivity in the licensed spectrum bands, and rely on dedicatedinfrastructure such as cell towers and backhaul equipment to connect tothe Internet.

As more users rely on the Internet to telecommute, communicate withfriends and family, watch videos, listen to streamed music, and indulgeinto virtual/augmented reality experiences, the data traffic continuesto grow exponentially. In order to address the continuously growingwireless capacity challenge, the next generation of LAN and WAN systemsare expected to use wider bandwidths and higher carrier frequencies,primarily in the millimeter wave range, as listed in Table 1.

TABLE 1 Examples of millimeter-wave bands Frequency Bandwidth Bands[GHz] [GHz] [GHz] 24 GHz 24.25-24.45 0.200 24.75-25.25 0.500 28 GHz/LMDS 27.5-28.35 0.850  29.1-29.25 0.150   31-31.3 0.300 32 GHz 31.8-33  1.200 37 GHz 37.0-38.6 1.600 39 GHz 38.6-40   1.400 42 GHz 42.0-42.50.500 47 GHz 47.2-50.2 3.000 50 GHz 50.4-52.6 1.200 60 GHz 57-64 7.00064-71 7.000 70/80 GHz 71-76 5.000 81-86 5.000 90 GHz 92-94 2.90094.1-95.0 95 GHz  95-100 5.000 105 GHz 102-105 7.500   105-109.5 112 GHz 111.8-114.25 2.450 122 GHz 122.25-123   0.750 130 GHz 130-134 4.000 140GHz   141-148.5 7.500 150/160 GHz 151.5-155.5 12.50 155.5-158.5158.5-164  

BRIEF SUMMARY OF THE INVENTION

Disclosed embodiments are directed to a portable millimeter-wavewireless communications device. In one aspect, the invention may beimplemented as a smart-phone, a laptop computer or a tablet computerthat relies on millimeter-wave spectrum for wireless communications. Inanother aspect, the invention may be implemented as a module that isadded to an existing portable device such as a smart-phone, a laptopcomputer or a tablet computer to provide millimeter-wave communicationscapability. The module may be incorporated into a protectiveencapsulating case of such portable devices, and could include a batterythat is separate from that of the portable device.

According to disclosed embodiments, a module is configured to convert aportable wireless communications device to a millimeter-wave wirelesscommunications device. The module includes a plurality ofmillimeter-wave antennas configured to receive millimeter-wave signalsand at least one low-noise amplifier (LNA) configured to amplify thereceived millimeter-wave signals. The module includes a down-conversioncircuit configured to down-convert the amplified millimeter-wave signalsto sub-6 GHz signals and a plurality of coupling antennas configured tocouple the down-converted sub-6 GHz signals to a plurality of secondantennas inside the portable communications device. The module includesat least one switch which routes the coupled down-converted sub-6 GHzsignals to a WLAN processing circuit for processing.

According to disclosed embodiments, when the wireless communicationsdevice is in a receive mode, the switch routes the down-converted sub-6GHz signals to the WLAN circuit, and when the wireless communicationsdevice is in a transmit mode, the switch electrically disconnects thesecond antennas from the WLAN circuit.

According to disclosed embodiments, a portable millimeter-wave wirelesscommunications device is configured to transmit uplink signals at asub-6 GHz band and receive downlink signals at a millimeter-wave band,wherein the millimeter-wave band is widely separated from the sub-6 GHzband. The device includes a plurality of millimeter-wave antennasconfigured to receive millimeter-wave signals and at least one low-noiseamplifier (LNA) configured to amplify the received millimeter-wavesignals. The device includes a down-conversion circuit configured todown-convert the amplified millimeter-wave signals to sub-6 GHz signals.The device includes a switch configured to route the down-convertedsignals to a sub-6 GHz processing circuit when the device is in areceive mode and configured to route the down-converted signals to atleast one sub-6 GHz antenna when the device is in a transmit mode.

BRIEF DESCRIPTION OF THE DRAWINGS

Error! Reference source not found. illustrates a wireless network inaccordance with disclosed embodiments;

FIG. 2 illustrates 5 GHz frequency bands;

FIG. 3A-3C illustrate various sections of a wireless communicationsdevice in accordance with disclosed embodiments;

FIG. 4 illustrates a millimeter-wave module in accordance with disclosedembodiments; and

FIGS. 5, 6, 7A-7B, 8, 9A and 9B illustrate millimeter-wave modules inaccordance with other disclosed embodiments.

DETAILED DESCRIPTION

In one aspect, some disclosed embodiments are directed to a portablecommunications device that relies on millimeter-wave spectrum forwireless communications. The portable communications device may, forexample, be a smart-phone, a laptop computer, or a tablet computer. Inanother aspect, disclosed embodiments may be realized as a module thatis added to a conventional portable communications device such as asmart-phone, a tablet, or a laptop computer. The add-on module convertsa conventional communications device to a millimeter-wave communicationsdevice. The module may be incorporated into a protective encapsulatingcase commonly used for conventional portable devices. The module may bepowered by a battery that is separate from that of the portable deviceor may rely on the existing battery of the portable device.

According to disclosed embodiments, radio spectrum below 6 GHz is usedin the uplink relying on the existing hardware within the portabledevice, and higher millimeter-wave spectrum is used in the downlinkbased on the dedicated circuitry in the add-on module.

FIG. 1 illustrates an exemplary wireless network 100 in accordance withdisclosed embodiments. Wireless network 100 uses frequency f₁ for thedownlink in a licensed millimeter-wave band, such as, for example, the28, 37 or 39 GHz bands, and frequency f₂ for the uplink in a sub-6 GHzfrequency band such as, for example, the 5 GHz unlicensed ISM or UNIIbands.

Wireless network 100 includes base stations or access points 104 and 108connected to the Internet 112 through high-speed wired links 116. Thewired links 116 may, for example, include optical fiber links (e.g.,10-100 Gb/s) or other means (shown in FIG. 1 as “Backhaul links”).Access point 104 provides services to portable communication devices C0,C1 and C2 on a first frequency f₁ in the licensed millimeter-wave bands,such as the 28, 37 and 39 GHz bands, on the downlink, while a secondfrequency f₂ in the unlicensed sub 6 GHz bands is used on the uplink.Similarly, the access point 108 provides services to portablecommunication devices C3, C4 and a vehicle C5 on a first frequency f₁ inthe licensed millimeter-wave bands, such as the 28, 37 and 39 GHz bands,on the downlink, while a second frequency f₂ in the unlicensed sub 6 GHzband is used on the uplink.

In one aspect of the invention, access point 104 provides for a downlinkon a first frequency f₁ in the licensed millimeter-wave bands, such asthe 28, 37 and 39 GHz bands, and a second frequency f₂ in the unlicensedsub 6 GHz band serves for the uplink, while access point 108 providesdownlink on a first frequency f₁ at the licensed millimeter-wave bands,such as the 28, 37 and 39 GHz bands, and a third frequency f₃ in theunlicensed 5 GHz band serves for the uplink. It should be noted thatsuch use of millimeter-wave spectrum, wherein the same frequency f₁ maybe used by multiple links operating simultaneously in proximity to oneanother, is made possible through the employment of narrow-beam antennasand, in particular, electronically-steerable phased-arrays.

In another aspect of the invention, wireless access point 104 providesdownlink on a first frequency f₁ in the licensed millimeter-wave bands,such as the 28, 37 and 39 GHz bands, and a second frequency f₂ in theunlicensed 5 GHz band is used on the uplink, while wireless access point108 provides for a downlink on a third frequency f₃ in the licensedmillimeter-wave bands, such as 28, 37 and 39 GHz bands, and a fourthfrequency f₄ in the unlicensed 5 GHz band serves for the uplink.

According to some embodiments, the first frequency f₁ used for thedownlink is one of the milliliter-wave frequencies in the 28 GHzlicensed band depicted in Table 1, while the second frequency f₂, usedfor the uplink can either be in the sub-6 GHz bands (e.g., one of the 5GHz frequencies, as depicted in FIG. 2, or is in one of themillimeter-wave bands listed in Table 1. It shall be assumed generallythat the first frequency used in the downlink is one of the millimeterwave bands shown in Table 1 and the second frequency used in the uplinkis 5 GHz unlicensed band depicted in FIG. 2.

FIG. 3A-3C illustrate various sections of a wireless communicationdevice in accordance with disclosed embodiments. The wirelesscommunication device is configured to receive at frequency f₁ in one ofthe licensed millimeter-wave (mmW) bands on the downlink, such as the28, 37 and 39 GHz bands, and to transmit at frequency f₂ in theunlicensed sub-6 GHz band on the uplink.

FIG. 3A shows a top view of the wireless communication device includingdisplay screen 308. The wireless communications device includesmillimeter wave receive module 312 shown in FIG. 3B and WLAN module 350shown in FIG. 3C.

Referring to FIG. 3B, millimeter wave receive module 312 includesmillimeter wave (mmW) antenna arrays 320 and 324 configured to receivemmW signals. The received mmW signals are amplified by mmWlow-noise-amplifiers (LNA) 328 and 332. The amplified mmW signals aredown-converted to sub-6 GHz band by a pair of mixers 336 and 340 drivenby phase-locked-loop (PLL) 344.

Referring to FIG. 3C, the 5 GHz signals from mixers 336 and 340 arerouted through switches S₁ and S₂ to WLAN module 350 for processing. Theswitches S₁ and S₂ are controlled such that when it is in transmit mode,the switch is in position 1 (connected to WLAN antennas 360 and 364),and when it is in receive mode, the switch is in position 2 (connectedto mmW module 312). Thus, the wireless communication device usesswitches S₁ and S₂ to receive at frequency f₁ in the licensedmillimeter-wave bands in the downlink by switching to mmW receivermodule 312, and transmit at frequency f₂ in the unlicensed sub 6 GHzband on the uplink by switching to antennas 360 and 364.

Since the isolation between switch positions 1 and 2 is limited, theamplified and down-converted sub-6 GHz received signal from the mmWantennas 320 and 324 can couple to the sub-6 GHz transmit antennas 360and 364 respectively degrading the out of band emission at sub-6 GHzband. According to some disclosed embodiments, when the switch is inposition 1, a control signal from the WLAN module 350 is used to disableor power down LNAs 328 and 332 either through an enable input or byturning off the power supply to LNAs 328 and 332 to avoid the out ofband emission at sub-6 GHz band.

According to some disclosed embodiments, a third switch on the mmWreceiver paths after mixers 336 and 340 is opened when the main switchis in position 1. According to yet other disclosed embodiments, theoutput of the PLL is disabled in the mmw module such that there is nodown-conversion from the mmW input to WLAN band.

FIG. 4 illustrates millimeter wave module 400 in accordance withdisclosed embodiments. Receive module 400 receives at frequency f₁ atthe licensed mmW bands such as, for example, 28, 37 and 39 GHz bands,using coupling antennas 404 and 408, and transmits at frequency f₂ inunlicensed sub-6 GHz band on the uplink. Coupling antennas 404 and 408operate according to the principle of mutual inductive coupling totransfer signals between the coupling antennas 404 and 408 and the WLANsub-6 GHz antennas 360 and 364. The over-the-air received signals atfrequency f₁ at the licensed mmW bands such as, for example, 28, 37 and39 GHz bands at mmW antenna array 412 and at mmW antenna array 416 areamplified by mmW low-noise-amplifiers (LNAs) 420 and 424.

The amplified mmW signals are down-converted to 5 GHz band by mixers 428and 432 driven by phase-locked-loop (PLL) 436. A filter such as acoupled line filter (not shown in FIG. 4) may precede the mixer tosuppress the image frequencies at 18, 27 and 29 GHz or 38, 47 and 49GHz, as determined by a local oscillator (low-side or high-sideinjection) frequency. Alternatively, in the absence of such interferers,the filter can be removed entirely to facilitate reduction in insertionlosses and in implementation dimensions. The resulting down-convertedsignals at 5 GHz can optionally be amplified by variable gain amplifiers(VGA) 440 and 444. These amplified 5 GHz frequency signals are coupledto WLAN/WiFi antennas using coupling antennas 404 and 408 and the WLANsub-6 GHz antennas 360 and 364. A WiFi transceiver (shown in FIG. 3C)processes these signals as if they were directly received over the airat 5 GHz. The gain setting for the VGAs can be controlled based on thepower level of the signals at the output of the mixers or via externalcontrol based on the signal level sensed by the WiFi receiver (not shownin FIG. 4). Fixed gain amplifiers may also be used as an alternative tothe VGAs.

Referring to FIG. 4, millimeter wave module 400 may be disabled when theWLAN transceiver (shown in FIG. 3C) is in transmit mode. Since thesignal received in the mmW band is amplified and mixed down to theunlicensed band and radiated through the coupling antenna, degrading outof band emissions may emanate from the portable device. According todisclosed embodiments, a TX/RX switch control signal from the WLANtransceiver may be used to power down the mmW signal path while the WLANtransceiver is in a transmit mode. An additional switch in the mmW pathmay be used or the LNA may be turned off.

According to disclosed embodiments, the coupling can be kept weak suchthat the performance of the main WLAN antennas on the smartphones arenot noticeably degraded by making the coupling antenna small such as tomodify the radiation characteristics of the WLAN antennas only slightly.Potential changes in the impedance of the WLAN antennas may becompensated for by an antenna tuner that is typically present in thecellphone to determine the best values of the tuning elements in thetuner network that would bring the composite WLAN and coupling antennasto the desired impendence value.

According to yet another disclosed embodiment illustrated in FIG. 5, inmillimeter wave module 500 microcontroller unit (MCU) 504 controls PLL508 to set the appropriate frequency for converting between 28 and 5GHz. MCU 504 also powers up/down sequence and a phase shifter inputs forbeamforming.

In yet another embodiment shown in FIG. 6, mmW module 600 also transmitsat frequency f₂ in the unlicensed 5 GHz band. In this embodiment, mmWmodule 600 also acts as a repeater at frequency f₂ in the unlicensed 5GHz band in the uplink. Referring to FIG. 6, module 600 receives atfrequency f₁ in one of the licensed mmW bands, such as the 28, 37 and 39GHz bands, and transmits at frequency f₂ in the unlicensed sub-6 GHzband in the uplink direction. MmW module 600 then receives at f₂ in theuplink and amplifies it and transmits through repeater antennas 604 and608. Coupling antennas 612 and 616 are switched between receiving thesignal from module 600 in the uplink and transmitting the signal tomodule 600 in the downlink. The switching control can either come frommodule 600 based on a control signal from the WLAN transceiver (notshown in FIG. 6) or may be based on direction-detection in mmW module600.

According to disclosed embodiments, switch control is used to turn offthe voltage supply to the LNA (or to disable it by a control input inthe mmW module in the TX mode or by opening a switch in its path suchthat the down converted signal from the mmw band does not spuriouslyradiate through the TX path in the TX mode, thereby degrading theout-of-band emission performance.

FIGS. 7A and 7B illustrate yet another embodiment of the invention. FIG.7A illustrates mmW module 704 comprising circulators (referred to as“directional couplers”) 708 and 712 used to decouple the transmit andreceive signals in mmW module 704. FIG. 7B shows WLAN module 740comprising WLAN antennas 744 and 748. In operation, 5 GHz transmitsignals from WLAN antennas 744 and 748 are captured by mmW module 704using 5 GHz coupling antennas 716 and 720 and the captured signals areretransmitted by 5 GHz transmit antennas 724 and 728. Directionalcouplers 708 and 712 ensure that the captured 5 GHz signals do not leakthrough the mmW circuitry to the 5 GHz down-conversion circuitry 732 and736.

The received mmW signals at millimeter wave antenna arrays 750 and 754are down-converted from mmW to 5 GHz by the down-conversion circuitry732 and 736 and forwarded to the 5 GHz coupling antennas 716 and 720.The 5 GHz coupling antennas 716 and 720 then transmit these signalstowards the WLAN 5 GHz antennas 716 and 720. These signals are thenprocessed as if they were received as WLAN 5 GHz signals fromover-the-air. Out of band spurious emissions can be reduced by turningoff the mmW RX path during TX mode.

In another embodiment of the invention, a smartphone transmits atfrequency h in the licensed band in the uplink. FIG. 8 illustrates amillimeter wave module 800 inside a smartphone. The mmW module 800receives at frequency f₁ in one of the licensed mmW bands, such as the28, 37 and 39 GHz bands, and also transmits at frequency f₁ in theuplink. The mmW module 800 then receives at f₂ in the uplink from thecoupling antennas 804 and 808 and amplifies it and up-converts it to mmWfrequency f₁ and transmits it through the mmW antennas 812 and 816. ThemmW antennas 812 and 816 are shared between the transmitter and receiverand switched through the same control for the coupling antennas 804 and808.

In another embodiment of the invention, the uplink and downlink mmWantennas are separated, thus eliminating the need for switching the mmWtransmitting signal and receiving signal to/from the antennas. In suchembodiment, the uplink and downlink mmW frequencies can be different,i.e. f₁ and f′₁. The PLL is switched quickly between TX and RX to centerthe local oscillator for transmitting at f₁ and receiving at f′₁.

FIGS. 9A and 9B illustrate yet an embodiment, which is a variation ofthe embodiment previously illustrated in FIGS. 3A, 3B and 3C. Referringto FIG. 9A, millimeter wave receive module 312 includes millimeter wave(mmW) antenna arrays 320 and 324 configured to receive mmW signals. Thereceived mmW signals are amplified by mmW low-noise-amplifiers (LNA) 328and 332. The amplified mmW signals are down-converted to sub-6 GHz bandby a pair of mixers 336 and 340 driven by phase-locked-loop (PLL) 344.Referring to FIG. 9B, the sub-6 GHz signals from mixers 336 and 340 arerouted directly to sub-6 GHz processing circuit 350. In contrast to theembodiment illustrated in FIGS. 3A, 3B and 3C, in this embodiment ofFIGS. 9A and 9B, the sub-6 GHz signals from mixers 336 and 340 arerouted to processing circuit 350 without the aid of switches. The sub-6GHz processing circuit may, for example, be a WLAN chipset.

Although embodiments of the invention have been described forimplementation in a smartphone, it will be appreciated by those skilledin the art that the principles of the invention also apply to otherportable devices such as Tablets and Laptops etc.

Those skilled in the art will recognize that, for simplicity andclarity, the full structure and operation of all systems suitable foruse with the present disclosure is not being depicted or describedherein. Instead, only so much of a system as is unique to the presentdisclosure or necessary for an understanding of the present disclosureis depicted and described. The remainder of the construction andoperation of the disclosed systems may conform to any of the variouscurrent implementations and practices known in the art.

Of course, those of skill in the art will recognize that, unlessspecifically indicated or required by the sequence of operations,certain steps in the processes described above may be omitted, performedconcurrently or sequentially, or performed in a different order.Further, no component, element, or process should be consideredessential to any specific claimed embodiment, and each of thecomponents, elements, or processes can be combined in still otherembodiments.

It is important to note that while the disclosure includes a descriptionin the context of a fully functional system, those skilled in the artwill appreciate that at least portions of the mechanism of the presentdisclosure are capable of being distributed in the form of instructionscontained within a machine-usable, computer-usable, or computer-readablemedium in any of a variety of forms, and that the present disclosureapplies equally regardless of the particular type of instruction orsignal bearing medium or storage medium utilized to actually carry outthe distribution. Examples of machine usable/readable or computerusable/readable mediums include: nonvolatile, hard-coded type mediumssuch as read only memories (ROMs) or erasable, electrically programmableread only memories (EEPROMs), and user-recordable type mediums such asfloppy disks, hard disk drives and compact disk read only memories(CD-ROMs) or digital versatile disks (DVDs).

Those skilled in the art to which this application relates willappreciate that other and further additions, deletions, substitutionsand modifications may be made to the described embodiments.

1. A millimeter wave wireless communications device configured to transmit uplink signals at a sub-6 GHz band and receive downlink signals at a millimeter wave band, wherein the millimeter wave band is widely separated from the sub-6 GHz band, the device comprising: plurality of millimeter wave antennas configured to receive millimeter wave downlink signals; at least one low-noise amplifier (LNA) configured to amplify the received millimeter wave band signals; a down conversion circuit configured to down-convert the amplified millimeter wave band signals to sub-6 GHz signals; and a sub-6 GHz processing circuit configured to process the down converted sub-6 GHz signals.
 2. The wireless communication device of claim 1, wherein the millimeter wave signals have frequencies of 24 GHz or higher.
 3. The wireless communication device of claim 1, wherein the down conversion circuit comprises at least one local oscillator driven by a phase locked loop (PLL).
 4. The wireless communication device of claim 1, wherein the LNA is disabled when the device is in a transmit mode.
 5. The wireless communication device of claim 1, further comprising a switch operable to route the sub-6 GHz signals to the sub-6 GHz processing circuit when the device is in a receive mode.
 6. The wireless communications device of claim 1, further comprising a plurality of sub-6 GHz antennas configured to transmit sub-6 GHz uplink signals.
 7. The wireless communications device of claim 1, wherein the sub-6 GHz processing circuit is a WLAN processing circuit.
 8. A millimeter wave wireless communications device configured to transmit uplink signals at a sub-6 GHz band and receive downlink signals at a millimeter wave band, comprising: a plurality of millimeter wave band antennas configured to receive millimeter wave downlink signals; at least one low-noise amplifier (LNA) configured to amplify the received millimeter wave downlink signals; a down-conversion circuit configured to down-convert the amplified millimeter-wave signals to sub-6 GHz signals; and a switch configured to route the down-converted signals to a sub-6 GHz processing circuit when the device is in a receive mode and to route sub-6 GHz uplink signals to at least one sub-6 GHz antenna when the device is in a transmit mode.
 9. The device of claim 8, wherein the sub-6 GHz processing circuit is a WLAN processing circuit.
 10. The device of claim 8, wherein the switch electrically disconnects the down-conversion circuit from the sub-6 GHz processing circuit when the device is in a transmit mode.
 11. The device of claim 8, wherein the millimeter-wave band signals have frequencies of 24 GHz or higher.
 12. The device of claim 8, wherein the down-conversion circuit comprises at least one local oscillator driven by a phase locked loop (PLL).
 13. The device of claim 8, wherein the LNA is disabled when the device is in a transmit mode.
 14. A wireless communication apparatus, comprising: a millimeter wave module comprising: a first antenna configured to receive millimeter wave band downlink signals; a down-conversion circuit configured to down-convert the millimeter-wave band downlink signals to first sub-6 GHz band signals; a first coupling antenna configured to couple the first sub-6 GHz band signals; a sub-6 GHz module comprising: a second coupling antenna, wherein the first sub-6 GHz band signals are transferred from the first coupling antenna to the second coupling antenna; and a sub-6 GHz circuit configured to process the first sub-6 GHz band signals.
 15. The wireless communication apparatus of claim 14, further comprising a directional coupler configured to transfer the first sub-6 GHz band signals from the down-conversion circuit to the first coupling antenna.
 16. The wireless communication apparatus of claim 14, wherein the first sub-6 GHz band signals are transferred from the first coupling antenna to the second coupling antenna via electromagnetic coupling.
 17. A wireless communication apparatus, comprising: a sub-6 GHz module comprising: a sub-6 GHz circuit configured to generate a first sub-6 GHz band signals; a first coupling antenna configured to couple the first sub-6 GHz band signals; a millimeter-wave module comprising: a second coupling antenna, wherein the first sub-6 GHz band signals are transferred from the first coupling antenna to the second coupling antenna; and a third antenna configured to transmit the first sub-6 GHz band signals as sub-6 GHz band uplink signals.
 18. The wireless communication apparatus of claim 17, further comprising a directional coupler configured to transfer the first sub-6 GHz band signals from the second coupling antenna to the third antenna.
 19. The wireless communication apparatus of claim 17, wherein the first sub-6 GHz band signals are transferred from the first coupling antenna to the second coupling antenna via electromagnetic coupling.
 20. A millimeter-wave wireless communications device configured to transmit uplink signals at a millimeter-wave band and receive downlink signals at a millimeter-wave band, comprising: a millimeter-wave antenna configured to receive millimeter-wave band downlink signals and to transmit millimeter-wave band uplink signals; at least one low-noise amplifier (LNA) configured to amplify the received millimeter-wave band signals; a down conversion circuit configured to down-convert the amplified millimeter-wave band signals to first sub-6 GHz signals; and a coupling antenna configured to couple the first sub-6 GHz signals and to couple second sub-6 GHz signals; an up-conversion circuit configured to up-convert the second sub-6 GHz signals to millimeter-wave band uplink signals; a power amplifier configured to amplify the millimeter-wave band uplink signals, wherein the millimeter wave band uplink signals are transmitted by the millimeter-wave band antenna.
 21. A method of wireless communication, comprising: receiving millimeter wave band downlink signals; amplifying the received millimeter wave band downlink signals; down-converting the millimeter wave band downlink signals to a first sub-6 GHz signals; routing the first sub-6 GHz signals to a sub-6 GHz processing circuit; generating a second sub-6 GHz signals; and transmitting the second sub-6 GHz signals as uplink signals.
 22. The method of claim 21, wherein a switch is configured to route the first sub-6 GHz signals to the sub-6 GHz processing circuit during a receive mode and to route the second sub-6 GHz signals to at least one sub-6 GHz antenna during a transmit mode.
 23. The method of claim 21, wherein the switch electrically disconnects a down-conversion circuit from the sub-6 GHz processing circuit during a transmit mode.
 24. A method of wireless communication, comprising: receiving, by a millimeter wave module, millimeter wave band downlink signals; down-converting the millimeter wave band downlink signals to first sub-6 GHz signals; coupling the first sub-6 GHz signals to a sub-6 GHz module; generating, by the sub-6 GHz module, second sub-6 GHz signals; coupling the second sub-6 GHz signals to the millimeter wave module; up-converting the second sub-6 GHz signals to millimeter wave uplink signals; and transmitting, by the millimeter wave module, the millimeter wave uplink signals.
 25. The method of claim 24, wherein the first sub-6 GHz signals are coupled by a first coupling antenna to a second coupling antenna, and wherein the millimeter wave module and the sub-6 GHz modules comprise the respective first and second coupling antennas.
 26. The method of claim 24, wherein the second sub-6 GHz signals are coupled by a second coupling antenna to a first coupling antenna, and wherein the millimeter wave module and the sub-6 GHz modules comprise the respective first and second coupling antennas. 